Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

readOnlyHint=true already establishes the safe-read profile, so the bar is lower. The description adds genuine value beyond that by disclosing the underlying endpoint (GET /businesses/{businessId}/opening-hours) and the shape of the values returned (seconds from midnight), which tells an agent how to interpret the response without an output schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, zero filler, with the semantically important detail (days and seconds from midnight) front-loaded before the API reference. Every sentence earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema present, the description usefully compensates by describing the returned fields and units. What remains uncovered is minor for a single-optional-parameter read tool, though a note on error/empty behavior would have completed it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and there is only one optional parameter, so the schema already carries the semantics including the 'default: the business you entered at login' behavior. The description adds nothing about business_id, making the baseline 3 appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description gives a specific verb+resource ('List the opening hours of the business') and clarifies the return shape (days plus start/end in seconds from midnight), which meaningfully disambiguates it from availability-style siblings like get_booking_days and get_booking_slots. It stops short of explicitly contrasting itself with those siblings, so a 4 rather than a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: an agent can infer this is the tool for business hours rather than bookable slots, but the description never states when to pick it over get_booking_days/get_booking_slots or what prerequisites exist. No exclusions or alternatives are named.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.